A New Bioconsortia Containing Antibiotics and ACC ‐Deaminase Producing Fluorescent Pseudomonad Strain Mixtures for the Simultaneous Management of Biotic and Abiotic Stress in Cotton

Biotic (root rot and wilt diseases) and abiotic (parawilt) stresses are the major constraints in cotton production. Microbe‐based biological control offers an alternative to chemical control, leading to the ecologically sustainable management of both biotic and abiotic stresses. A total of 30 fluorescent pseudomonad strains were isolated from cotton rhizospheres and their biocontrol efficacy against Rhizoctonia solani and Fusarium oxysporum f. sp. vasinfectum was evaluated in vitro. The APKP4 and VPNP5 isolates were significantly superior in inhibiting the mycelial growth of wilt and root rot pathogens, respectively. Further, fluorescent pseudomonad strains APKP4, VPNP5 and KYIP5 showed greater performance in improving the plant growth parameters of cotton seedlings in vitro. These strains showed efficient production of growth hormones such as indole‐3‐acetic acid (IAA) and 1‐aminocyclopropane‐1‐carboxylate deaminase (ACCD). The antifungal metabolites, 2,4‐diacetylphloroglucinol and phenazine extracted from these isolates also showed higher antagonistic activity against F. oxysporum f. sp. vasinfectum and R. solani . Furthermore, the antagonistic fluorescent pseudomonads effectively produced lytic enzymes and antimicrobial traits such as chitinase, cellulase, protease, amylase, gelatinase, siderophore and hydrogen cyanide. The talc‐based formulation of promising fluorescent pseudomonad strains was evaluated individually and in combination against root rot, wilt and parawilt of cotton under field conditions. Among the treatments, the bioformulation mixture (APKP4 + VPNP5 + KYIP5) containing both antibiotics and ACC‐deaminase‐producing fluorescent pseudomonad strains recorded the minimum incidence of root rot, wilt and parawilt, maximum plant growth and seed cotton yield. This study has the potential to be adopted for sustainable and environmentally friendly cotton production.